The packing nut will not loosen even with repeted applications of penetrating oil followed by tapping. If I keep going after it the way I have been doing - with pipe wrenches - I'm going to round the brass.
Has anyone used the adjustable packing nut wrench from West Marine? It looks to be the best one of the lot. Any comments good or bad? The handle looks sort of short. Maybe it needs a piece of pipe on it. Also can the same wrench be used to loosen the lock nut?

I use the adjustable slip nut wrench like the one at WM. But I got mine at the local Big Box store in the plumbing section for less money. Get two. One to hold the packing gland stationary and one to turn the follower. Make sure the lock nut is backed off.

One problem is that my wrenches with jaws that open wide enough are too long to fit in the available space. Should have done a practical test before putting them on board. (Similar to the jack I carried for years that wasn't tall enough to do the truck...)

This exact one is on order from home depot.
Has anyone had any luck getting the lock nut loose using one of these? If I can get the lock nut loose then I can tighten the packing nut a tad and get the excess drip stopped.

I've never had any luck using those adjustable sink wrenches on ANYTHING. The jaws won't stay fixed in position long enough to get them on the nuts and the whole apparatus is so big and clumsy you can't get it in anywhere.
I made my own stuffing box wrenches out of 3/16 steel using nothing but an angle grinder and they've worked well for 20 years.
Alternatively, get a couple of monkey wrenches at a flea market. You can grind down the jaws if they're too big.

Two small monkey wrenches always worked for me and I had a tight spot to work on. Just be careful on the thinner nut. Those sink wrenches were never meant for the kind of pressure you might need to break free a packing nut. Just my thoughts.